Cable scoring tool



Oct. 27, 1970 v J. J. MATTHEWS 3,535,785

CA BLE SCORING TOOL Filed Feb. 26, 1968 I 2 Sheets-Sheet 1 2T 5 F g INVENTOR.

JAMES J. MATTHEWS BY X 9;

ATTORNEY Oct. 27, 1970 J. J. MATTHEWS 3,535,785

CABLE SCORING TOOL Filed Feb. 26. 1968 2 Sheets-Sheet 2 INVENTOR. JAMES J. MATTHEWS ATTORNEY 'United States Patent Oflice 3,535,785 Patented Oct. 27, 1970 3,535,785 CABLE SCORING TOOL James J. Matthews, Hicksville, NY. (Landing Hill Road, East Aaddam, Conn. 06423) Filed Feb. 26, 1968, Ser. No. 708,275 Int. Cl. B21f 13/00; B26b 27/00 US. Cl. 30-912 10 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to apparatus for removing the shielding jacket from electrical conductors and, in particular, to a tool for scoring the semi-conducting jacket of high voltage cables preparatory to its manual removal therefrom.

High voltage electrical conductors comprise an inner core of wire, successively surrounded by a thin layer of dielectric or semi-conducting material, a thick layer of insulation such as polyethylene or polyvinylchloride, and, finally, a thin, but substantial jacket or shield of dielectric or semi-conducting material. The shield or semi-conducting jacket is laid on or molded about the thick insulation and thus is tightly formed about it. Thus, the jacket must be removed from the thicker insulation without marking, scoring or otherwise, in any manner, affecting the characteristics of such insulation.

The present invention has as its object the provision of a tool which easily scores the semi-conducting outer jacket of insulation preparatory to manually removing the same from the conductor.

The present invention has as a further object the provision of a tool which is capable of scoring the shielding layer of semi-conductive material in a special configuratlon.

It is a specific object of this invention to provide a tool capable of scoring electrical conductors of varying size.

It is another specific object of this invention to provide a scoring tool in which the scoring blade is adjustably mounted so that the depth of the score in the jacket may ba varied.

A further object of the invention is to provide a tool which will score the jacket to be removed without scoring or otherwise marking the insulation from which it is removed.

Various other objectives and advantages, as Well as those enumerated above, will be apparent and fully understood from the following description wherein reference is made to the accompanying drawings in which:

FIG. 1 is a perspective view of the tool of the present invention positioned about a conductor and scoring a portion of the outer jacket.

FIG. 2 is an end view of the device shown in FIG. 1,

FIG. 3 is a sectioned view of the device taken along line 33 of FIG. 2,

FIG. 4 and 4a are two views of the scoring element of the device taken along line 44 of FIG. 3,

FIG. 5 is a sectional view of the device taken along line 55 of FIG. 3,

FIG. 6 is a sectional view of the device taken along line 6-6 of FIG. 3, and

FIG. 7 is a perspective view of an electrical conductor which has been scored and partially removed of its outer jacket.

The device of the present invention is, in FIGS. 1 and 2, positioned about a cable 10, having a shielding jacket 12, and comprises elongated upper jaw member 14 and a lower jaw member 16, each having a pair of extending hinge arms 18 and 20, respectively, hingedly connected together through a pin 22. The lower jaw member 16 is provided with a second pair of arms 24 through which is secured a pin 26. An elongated screw 28 is fixed, at one of its ends, to the pin 26 between the arms 24. The screw 28 extends upwardly into and through a hub 30 formed on the upper jaw 14 and has its free end engaged within a corerspondingly internally threaded knob 32. A washer 34 is located between the ends of the knob 32 and the hub 30 so that the knob 32 may be easily rotated thereon to thread the screw 28 upward into it or project the same down outward to adjust the length of the screw 28 and thereby pivot the jaws 14 and 16 with respect to each other. Thus, the jaw members 14 and 16 may be adjustably clamped about the cable 10 by merely rotation of the knob 32.

The upper jaw 14 is V-shaped and has a smooth surface adpated to contact the cable along the entire lengths of portions A and B, as seen in FIG. 2. The lower jaw is curved and terminates along its edge in a longitudinal bead 36 which is adapted to contact the surface of the cable along its length at a position C as seen in FIG. 2. It will be observed that positions A, B and C form a triangular engagement with the circumference of the cable 10 and since they are elongated, they thus insure that the jaws 14 and 16 clamp a lengthwise extent of the cable securely and uniformly along the entire length of the device. The smooth surfaces of the jaws at points A, -B and C, however, permit the device to be rotated about the cable in either direction shown by the arrows -D in FIGS. 1 and 2. Furthermore, the adjustable jaws allow the device to be used on a variety of cables of different diameters.

Integrally formed on the upper surface of the upper jaw member 14 is a hollow cylindrical pedestal or post 38 having an external shoulder 40 along its base. The post 38 is further for-med internally with a shoulder 42 at its base and an internal shoulder 44 at its upper end. Slidably located within the post 38 and extending outwardly from the upper end is a cylindrical hollow knife carrier 46. The carrier 46 is provided with a substantially solid head 48 at its lower end, the inner surface of which is adapted to be limited in its upward movement by engagement with the lower shoulder 42 of the post 38. The head 48 is provided with a central bore through which extends the shaft 50 of an insulation scoring knife. One-half of the outer surface of the head 48, as seen in FIGS. 3 and 4, is formed with a series of parallel chordal serrations 52 while the other half of the head 48 is cut away to form a smooth surface 53 in a plane extending substantially shoulder 42 of the post 38 is a spring 54 adapted to bias tween the inner surface of the head 48 and the upper shoulder 42 of the post 38 is a spring 54 adapted to bias the carrier 46 normally downward.

Fitted over the outside of the post 38 is a knob 56 having an elongated depending cylindrical skirt. The knob 56 is formed coaxially with a first hollow section 58, second hollow sectional 60 and a third hollow section 62 of decreasing diameters. The larger diameter hollow section 58 is adapted to fit rotatably over the post 38 with the shoulder 63 formed between it and the next section 60 resting on the upper end of the post 38. The second section 60 is of a diameter which receives the carrier 46 therein. The last section 62 is of a relatively small diameter and is screw threaded along its entire length.

Extending radially through the wall of the knob 56 (FIGS. 2 and 6) is a set screw 64 which engages Within a positioning hole 66 formed in the outer wall of the knife carrier 46 of a width substantially equal to the diameter of the screw. This combination of screw 64 and the slot 66 acts to secure the carrier 46 to the knob 56 for reciprocal vertical movement of the carrier with the knob and for conjoint rotation. The bias of the spring 54 between the shoulder 44 and head 48 causes the head to project downward to its position shown in FIGS. 2 and 3. The connection of the set screw 64 between the carrier 46 and knob 56 serves to apply the spring bias to the knob to bring its lower end into abutment with the external shoulder 40. Thus, the set screw 64 secures the carrier 46 and knob 56 respectively within and also about the post 38.

Extending or disposed substantially radial relative to the cable and within the central bore of the carrier 46 is the knife shaft 50. The knife shaft 50 is needle shaped, i.e., long and thin, and has an oblong cutting or scoring edge 68, as seen in FIG. 4, formed at its lower end. The shaft 50 extends upwardly through the carrier 46 and terminates in a head 70 located within the small bore section 62 of the knob 56. A set screw 72 threaded into bore 62 limits the upward movement of the knife 50. Centrally of the knife shaft, there is secured an annular guard or stop member 74, between which and the internal lower end of carrier 46, is located a spring 76 that biases the knife shaft 50 upward againht the set screw 72. By adjusting the set screw 72 against the upward bias of spring 76 it is possible to extend or retract the oblong cutting edge 68 with respect to the outer face of the carrier head 48. Thus, the depth or extent of the cut into the jacket 12 can be precisely determined and controlled.

The lower portion of the knife shaft 50 is provided with a flat side 78, as seen in FIG. 5, extending along a substantial length. A positioning screw 80 is radially inserted through the head 48 before the same is secured in the knob 56 by the screw 64. The end of the screw 80 lightly and slidingly engages the flat surface 78 of the knife shaft and stabilizes the same against rotation relative to the carrier 46 but permits the same to move axially or vertically in the head 48 and carrier 46.

It will thus be observed that on rotation of the knob 56 relative to the post 38, the carrier 46 and knife shaft 50 are also rotated due to the engagement of the set screw 64 in positioning hole 66 and the engagement of the set screw 80 with the fiat side 78. It is preferred that the rotation of the carrier 46 and knife 68 be limited to two positions. The first, as seen in FIGS. 2, 3 and 4, is where the cutting edge 68 of the knife is transverse of the longitudinal axis of the device. This position will allow the cutting edge to score the jacket in a circle about the cable. The second position is illustrated in FIG. 4a. In this figure the cutting edge 68 is shown as being at an angle to both the transverse axis and the longitudinal axis of the cable. Such an angular position will allow the cutting edge 68 to cut spirally along the circumference of the cable.

Suitable indicia '82 representing the two positions of the blade are engraved on the surface of the lower edge of the knob 56 (FIG. 1). The shoulder is provided with a reference mark 84 engraved thereon for cooperative alignment with the indicia 82. The knob 56 is provided with a slot 86 along a portion of its lower extremity and the post 38 is provided with a pin 88 radially extending therefrom through and into the confines of the slot 86. The pin and slot arrangement act as a limiting or stop means for rotation of the knob 56 and, consequently, defines the position of the cutting edge 68 and limits the alignment of the indicia 82 with the stationary mark 84.

The vertical movement of the carrier 46 and knife shaft are effected by the vertical lifting of the knob 56, the shaft 50 being constantly biased upward against the set screw 72. The extent of the vertical movement of the knob 56 is limited by the upward engagement of the head 48 with the internal shoulder 42 of the post 38. The space between the shoulder 42 and the head 48 is such that the carrier 46 will not slide upwardly completely out of contact with the cable jacket but will be retained in contact therewith so that the serrations 52 will scratch or lightly score the surface of the jacket 12.

The purpose of the serrations is to act as a guide or tracking means for the device and to insure that the device, when rotated about the cable, maintains either a true circular movement thereabout or the circumferential spiral direction desired. The serrations are not designed to cut the jacket but rather to bite into or depress into it only the depth or extent that a threading motion is impared and, therefore, in this respect the constant of spring 54 must be critically designed. The smooth half 53 of the face of head 48 enables the head to move over the surface of the jacket without marring or bulging the unscored remaining portion of the jacket while rotation of the device about the cable is in progress, so that the portion of the jacket that will remain on the cable is left in its smooth and unscarred state.

In operation, the tool is first conditioned by presetting the position of the set screw 72 so as to determine the effective depth of the cutting edge 68. It is to be preferred that this depth would be sufficient to score substantially through the jacket insulation but not completely therethrough so as to avoid scoring or nicking the underlying insulation. Thus, the exact position of the set screw 72 will be determined by the operator of the device through empiric observation or acquired skill.

The tool is then placed about the cable and the jaws 14 and 16 clamped tightly about the circumference by rotation of the knob 32. It may be preferred that scoring of the cable jacket be made from the end of the cable inwardly, therefore, the tool is first placed so that the cutting edge 68 abuts the end of the cable 10 and the smooth surface of the carrier head 48 rests upon the cable. Since the cutting edge 68 will normally depend below the smooth surface 53 of the head, it will be easy to see whether the edge 68 will cut completely through the jacket thickness. Since it is also the object to score the jacket in a circumferential spiral to a position inwardly of the cable end, the knob 56 is rotated so as to position the head 48 and the oblong cutting edge 68 angular to the transverse and longitudinal axes of the cable.

The device is then rotated or moved bodily counterclockwise about the cable as indicated in the drawings and during this movement, the oblong cutting edge 68 cuts into the jacket material. As rotation of the device continues, the serrations 52 bite into the jacket at their preset angle to the axis of the cable to cause the device to progress in a spiral direction about the cable to score the jacket along the line 90 (FIGS. -1 and 7). As the spiral scoring continues, the serrated portion 52 of the head 48 engages the surface of the jacket material, biting into the same as at 92 to a lesser depth than the edge 68 and insuring the spiral tracking of the tool.

When a sufficient length of the cable is thus scored, the knob 56 is rotated so that the cutting edge 68 is positioned transversely of the longitudinal axis of the cable. The tool is thereupon rotated in a complete circle about the cable and the final perfectly circular scoring 94 is made as indicated in FIG. 7. The device is thereupon removed from the cable by loosening of the jaws 14 and 16. The scored insulation is then manually removed as indicated in FIG. 7. Once scoring is accomplished, removal of the jacket is accomplished relatively easy by lifting the same manually from the lower insulation. The scored jacket will be removed in a spiral form because of its spiral scoring.

It may also be preferred that the jacket scoring operation be made from a point along the cable to the end of the cable itself. In this case, the device is of course clamped about the cable at the particular point at which the jacket scoring is to begin. With the oblong knife 68 transverse to the cable axis, the device rotated to initially make the circular cut 94. The knob 56 is then rotated into the position where the cutting edge will produce the spiral cut 90 and the device is then rotated clockwise as seen in the figures of the drawings. The cutting may then proceed until the device progresses completely to the end of the cable and runs off the edge.

It will, of course, be appreciated that operation of the device is similar in either of the two rotational modes of operation and they are clearly interchangeable. However, if the scoring of the jacket is to be made between the ends of the cable, the knob 56 is rotated to cause the edge 68 to form an ending circular score about the jacket. The knob 32 is rotated to part the jaws 14 and 16 from the cable and the knob 56 is then lifted to raise the head 48 up to the limit of shoulder 42. This also raises the serrations 52 and the cutting edge 68 thereby assuring that they will not mark or scar the remaining portion of the cable jacket.

It will thus be seen from the preceding description that the tool provided by the present invention is simple in construction as well as in operation. The tool successfully and easily scores only the outer jacket of insulation preparatory to manual removal without endangering or subjecting the cable or insulation itself to any adverse mechanical action. Further, the tool is adaptable to adjust ment for varying size cable and/or jacket by operation of its adjustable clamp jaws and knife positioning means. It is capable of scoring in a variety of spiral configurations by adjustment of the cutting edge position.

While I have pointed out, by showing and describing a preferred form, the novel features of this invention, it will be understood that various modifications, substitutions and changes in form may be made without departing from the spirit thereof. For example, the adjustable jaw clamping means shown may be replaced by another body form such as a split yoke, separable semi-spherical halves, etc. The adjustable mechanism may be replaced by other locking or clamping mechanisms as might the mechanism of rotating and positioning the cutting edge. It is the intention, therefore, that this invention be limited only as indicated by the scope of the claims appended hereto.

I claim:

1. A tool for scoring the jacket of electrical cable comprising a body adapted to fit on said cable for rotation there about,

a knife mounted in said body having a cutting edge extending outwardly therefrom to pierce the surface of the jacket,

tracking means angularly adjustable relative to the longitudinal axis of the cable for biting engagement with the jacket,

means to position said cutting edge to pierce the surface of the jacket in accordance with the angular adjustment of said tracking means and to permit relative movement between said tracking means and knife with respect to the longitudinal axis of the cable While the cable jacket is being scored by the cutting edge,

and means to resiliently urge said tracking means into its engagement with the jacket.

2. The tool according to claim 1 wherein said body comprises a pair of opposed jaw members hingedly connected to fit about the cable,

and jaw positioning means for adjustably clamping said body about said cable.

3. The tool according to claim 2 wherein one jaw member has a V-shape adapted to engage the cable at two points and said other jaw member is curved and adapted'to engage said cable at a third point opposed to said first two points.

4. The tool according to claim 1 including means for adjusting the extent of said cutting edge outwardly of said body.

5. The tool according to claim 1 in which said body is formed with a hollow pedestal,

and the means for mounting said knife forming a part of said tracking means having a hollow knife carrier reciprocally slidable in said pedestal,

said knife being axially mounted within said carrier and having its cutting edge extending outwardly therefrom,

resilent means urging said knife inwardly of said carrier,

and adjustable stop means engaging the head of said knife for limiting the inward movement thereof.

6. The tool according to claim 5 wherein the pedestal and carrier are cylindrical and relatively rotatable and including means for rotating said carrier so as to position the oblong cutting edge angularly with respect to the longitudinal axis of the cable.

7. The tool according to claim 6 wherein said carrier is provided with a coaxial knob for manually rotating said carrier,

said knob including indicia for locating the position of the cutting edge.

8. The tool according to claim 7 including means limiting the extent of rotation of said knob.

9. A tool for scoring the surface of a cable comprising means to clamp the tool to a cable to be scored and for relative movement of said tool and cable, scoring means on said tool disposed substantially radial to the clamped cable to score the surface thereof, means on said tool to predeterminately adjust said scoring means to a depth of penetration of the clamped cable,

tracking means for biting engagement with the cable surface,

means resiliently urging said tracking means into engagement with the cable,

means on said tool and operatively connected with said scoring and tracking means to rotate said scoring and tracking means between a position transverse to the longitudinal axis of the clamped cable and a position angular to the longitudinal axis of the clamped cable,

and means between said scoring and tracking means to move the same conjointly to their transverse and angular positions and to permit relative radial movement therebetween while the cable is being scored by the scoring means.

10. A tool as in claim '9,

means on said tool to limit the rotation of said scoring and tracking means.

References Cited UNITED STATES PATENTS 2,778,105 1/1957 Carta 3090.7

3,082,523 3/1963 Modes 3090.7 X

3,215,007 11/1965 Stallings 30--90.9 X

JAMES L. JONES, JR., Primary Examiner US. Cl. X.R. 

